President Obama and top Democrats set out Thursday to thwart defections and solidify support for their health care overhaul bill, focusing on skeptical rank-and-file House Democrats antsy about voting for the unpopular measure and then having to fend off Republican attacks in the midterm elections.

A dozen House Democrats who supported the bill in the House said they’ll vote against Mr. Obama’s plan unless strong abortion restrictions are inserted. Others question whether the Senate bill, the basis of the president’s plan, will do enough to stem rising health care costs or address regional disparities on Medicare rates.

Nearly 20 House Democrats were called to back-to-back White House meetings with Mr. Obama in which he told the rank and file that “to maintain a strong presidency, we need to pass this bill,” said Rep. Raul M. Grijalva, Arizona Democrat and co-chairman of the Progressive Caucus.

Mr. Obama asked them to put aside political concerns and appealed to their sense of duty and history to deliver a comprehensive overhaul of the nation’s health care system, said people who attended.

But Republican lawmakers, who universally oppose the bill, vowed to capitalize on it in November. The National Republican Congressional Committee created a “Code Red” project to ensure that supporters of the bill “pay a price in November.” Polls show the majority of Americans oppose the plan as written.

“Code Red is the vehicle that will ensure that Democrats are held accountable for supporting a reckless agenda that is overwhelmingly opposed by the people who elected them,” said NRCC spokesman Ken Spain.

Former Democratic National Committee Chairman Howard Dean said the Senate bill would harm vulnerable Democrats more than help them.

“The plan, as it comes from the Senate, hangs out every Democrat who’s running for office to dry - including the president, in 2012, because it makes him defend a plan that isn’t in effect essentially yet,” the former physician told “The Bill Press Radio Show.”

Much of the Senate’s bill doesn’t go into effect for years.

White House spokesman Robert Gibbs said the House is on track for a vote by March 18, when Mr. Obama leaves for an Asian trip, but the office of House Speaker Nancy Pelosi, California Democrat, declined to release a deadline.

The Senate bill is expected to be the basis for Democrats’ aggressive plan to get the health care plan through Congress. It would require House Democrats to cast a politically risky vote for the Senate bill with little more than a promise that the Senate would be able to pass the companion bill to change controversial provisions such as a tax on high-cost insurance plans and carve-outs critics say were designed to curry votes.

In an attempt to assuage those concerns, Mr. Obama told a group of House members that he intends to sign two bills - the Senate bill and the repair package - and, in a nod to liberals, pledged to try to work on a public option bill in the future, Mr. Grijalva said Thursday.

The House health bill passed by a 220-215 vote, leaving Democrats with just a three-vote cushion of the 217 they need to keep on board to pass the Senate bill.

But a dozen of those “aye” votes will vote against the Senate bill unless strict language is added that would prevent federal funding of abortions, similar to restrictions they were able to get into the House bill over Mrs. Pelosi’s objection, said Rep. Bart Stupak, Michigan Democrat.

“Let’s face it: I want to see health care,” he told “Good Morning America” on Thursday. “But we’re not going to bypass some principles and beliefs that we feel strongly about.”

Mr. Gibbs, as well as Mrs. Pelosi, said Thursday that the Senate bill does not allow for federal funding of the procedure.

Rep. Daniel Lipinski, Illinois Democrat and one of the 12 who oppose the Senate bill, said he hasn’t been lobbied to change his mind.

“They all know where I stand,” he said. “I will not vote for a health care bill that funds abortion, and the Senate bill does.”

At stake is the biggest policy initiative of the year-old Obama presidency, a rewrite of the nation’s health care system that would trim hundreds of billions of dollars from Medicare, expand Medicaid, mandate that every American join a plan and rewrite rules telling insurance companies how they can operate.

The House and Senate have passed their own versions of bills, but the debate has been stalled for nearly two months after Democrats lost their filibuster-proof majority in the Senate in January.

Mrs. Pelosi said she expects her members’ concerns to be addressed in the companion bill Democrats plan to pass through the Senate using reconciliation rules that would prevent a Republican filibuster.

“I feel very confident that the up-or-down vote on the majority-rule proposal that will come to the House will satisfy members’ concerns about the Senate bill,” she told reporters.

Senate Republicans, hoping to take advantage of House Democrats’ skepticism, warned that they plan to make reconciliation as difficult as possible, using every delaying tactic available to them, which could leave Mr. Obama with no choice but to sign the Senate bill into law with no repairs.

“And, Harry Reid will have no incentive to catch them because by the time he gets to the reconciliation bill, the president will have already signed the health care bill into law,” Mr. Alexander said.

Underscoring the close vote expected, Rep. Nathan Deal, Georgia Republican, said Thursday that he’ll delay his resignation from the House at least through this month so that he can vote against it.

Mr. Deal said Monday that he planned to resign to focus on his gubernatorial bid, but delayed his departure upon hearing that Democrats plan to hold a vote on the health care bill within weeks.

Meanwhile on Thursday, the White House sharpened its critique of insurance company profits, which Democrats say are a central reason to pass a reform bill. Health and Human Services Secretary Kathleen Sebelius asked the nation’s largest health insurers at a White House meeting to justify recent double-digit premium hikes across the country.